<!DOCTYPE html>
<style>
  #outer {
    height: 500px;
    width: 500px;
    background-color: blue;
    border-style: solid;
    border-color: gray;
    border-radius: 50px;
    border-width: 10px;
    overflow: hidden;
  }
</style>
<div id="outer">
    <div style="background-color: green; position: relative; width: 600px; height: 480px; top: 10px; left: 0">
    </div>
</div>
